1. Field of the Invention
The present invention relates to a remote program downloading system for remotely rewriting software installed into an apparatus connected to a network via a digital transmission path.
2. Description of the Related Art
In order to achieve a digital broadcast, notably digital satellite broadcast, digital broadcast receivers have been developed. In the digital broadcast receivers, software is executed therein to perform computer-related processing such as processing on digital video speech signals and display of electronic program guide corresponding to program schedule data.
In the digital broadcast, since broadcast contents are digitized, all data for use by computer is capable of being transmitted in addition to broadcast contents. Therefore, digital broadcast receivers are capable of receiving new software to be installed thereinto via broadcasts, and of substituting the new software for software currently executed therein. Such functions enable software of a digital broadcast receiver to be rewritten with the receiver lying in a house.
As such a remote downloading method via a broadcast, some methods have been proposed. For example, Japanese Laid-Open Patent Publication HEI11-102287 explains the remote downloading with attention principally focused on management of version.
Recently the provision of services has been considered such as online shopping and communication by e-mail with a digital broadcast receiver connected to a computer network via telephone lines and with the digital broadcast receiver used as a user interface. In other words, the digital broadcast receiver is going to be provided with not only current one-way service aspects for receiving broadcasts but also bi-directional service aspects as a telephone.
A remote downloading method via a bi-directional communication system is developed as a bank online system. For example, Japanese Laid-Open Patent Publication 2000-330779 proposes a patch method for downloading only an updated portion to reduce a communication time in a bank online system.
However, in the case of apparatuses, such as a digital broadcast receiver, mainly used in a house, the situation is different from that of the online system where an administrator of each terminal maintains close contact with the center, and cases occur frequently where power is not supplied to the digital broadcast receiver or the receiver is not connected to a communication channel at the time of remote downloading. Therefore, a large number of versions of current software exist which are executed in digital broadcast receivers targeted for remote downloading, resulting in a problem that there are enormous pieces of patch information to be managed on the center side.